JP2006508851A - Attenuator - Google Patents

Abstract

The attenuation device of the present invention comprises a surface of revolution (11) of circular cross section, such that a set of slots (14) is distributed between the sides of the surface of revolution (11) and adapted to confine an elastic material (15) within the limits defined by the slots (14), generating a structural labyrinth for load passage from a lower interface of the surface of revolution (11) to an upper interface. <IMAGE>

Description

  The present invention relates to a damping device for vibration and shock waves transmitted through a connecting structure included in a spacecraft.

  More particularly, the present invention relates to a passive damping device that reduces vibrations and shock waves that are generated and transmitted through the spacecraft structure during the flight of the spacecraft.

  A passive attenuating device is a known technique. For example, Patent Document 1 discloses a passive attenuating device that reduces vibrations and shock waves generated during a spacecraft flight.

  This passive damping device comprises a straight circular hollow cylinder, in which a set of rectangular slots are created and distributed in several vertical planes or layers.

  The horizontal slots are distributed so as to trace a helical space curve, i.e. not vertically aligned in the column. Each horizontal or horizontal layer is provided with a number of slots, in particular more than six slots.

  Each horizontal slot has an elongated rectangular shape, and in the rectangular horizontal slot, the vertical parallel side surface is smaller in size than the horizontal side surface.

  The slotted hollow cylinder is surrounded by several rectangular segments, which are made of a viscoelastic material and completely cover the slotted cylinder. The rectangular segments or sheets are surrounded on the outside so as to form a cylindrical ring that holds the sheet of viscoelastic material against the slotted hollow cylinder by several rectangular sheets made of rigid material.

  The disclosed adapter device has several disadvantages due to its structure. For example, one drawback is due to the large number of separations or bridges present in each horizontal layer and slotted hollow cylinder. A bridge or separation is to be understood as the part of the material that exists between two adjacent slots.

  A distribution with excessive axial symmetry in the number of slots and the number of bridges between slots can be seen. This translates into a loss of attenuation (even amplification) at a particular frequency associated with the eigenmode and axisymmetric support conditions of the cylindrical structure. This is illustrated in FIGS. 9-12 of U.S. Pat. No. 6,057,079 and illustrates the features of the proposed apparatus.

  In connection with this type of structure, the structural changes between the various layers, between the two ends and between adjacent structures are very abrupt (no stress distribution surface), Means overloading of the damping device seat and adjacent structures that must support large peak tensile / compressive stresses (overflow).

  Another disadvantage is the reduced stiffness due to the large number of horizontal layers and the large number of horizontal slots per layer. Rigidity is required for good control throughout the spacecraft flight and a compromise between damping and stiffness must be made. That is, the large number of layers and the number of slots mean greater attenuation, while mean less stiffness, resulting in a compromise between spacecraft compartment and load capacity.

  On the other hand, the outer cylinder floating on the viscoelastic material has little effect on the overall stiffness of the device. Similarly, there is almost no influence on attenuation. External loads induce relative movement between different layers. These movements cause shear deformation in the viscoelastic material. However, these deformations are about half the movement that occurs between the upper and lower interfaces and do not amplify the effect on the shear force.

The biggest drawback of this structure is that it cannot meet the conflicting requirements of damping and stiffness. Based on actuation in linear load deformation behavior (metal and viscoelastic components), any increase in stiffness results in a decrease in damping capacity and vice versa.
US Pat. No. 6,2029,261

  Therefore, there is a need to develop a damping device that dampens high and low frequency vibrations and shock waves and provides the lowest level of stiffness that can achieve accurate spacecraft guidance without affecting the damping capability. .

  The damping device of the present invention comprises a rotating surface having a circular cross section, and a set of slots is distributed between both surfaces of the rotating surface so as to confine the elastic material within the range formed by the slots. Yes.

  It is an object of the present invention to provide a structural labyrinth for passing loads from the lower interface of the rotating surface, such as a straight hollow cylinder, to the upper interface.

  Another object is to ensure that the elastic material and the remaining material of the rotating surface form two consecutive complementary labyrinth structures, i.e. there is an elastic material and no material corresponding to the rotating surface. , Or vice versa, filling the slot cavities with elastic material.

  Using this device, a compact and lightweight structure is achieved, the structure acting as a block of matrix corresponding to a composite material, i.e. elastic material, and fibers corresponding to a rotating surface, each element being for example Cylindrical rotating surface material acts as a fiber that provides stiffness, and elastic material serves as a matrix that complements stiffness and provides energy dissipation capability.

  Another advantage of the present invention is that the elastic damping means forms part of the structure itself, the elastic damping means being integrated along the entire surface and shuttle and / or artificial. It is adjustable for large diameter interfaces found in spacecraft such as satellites. Therefore, long and low frequency and medium frequency vibrations (0-2000Hz) lasting about a few minutes induced by the engine and the periodic operating elements, and a very wide spectrum (up to 10000Hz) but 1/1000 second A short-time transition phenomenon such as an impact induced by no separation that generates vibration that is time is attenuated and damped.

  The advantage of this device is that the contribution of each element can be adjusted to best suit the usage requirements. If less stiffness is required with greater dissipation capability, it is sufficient to increase or decrease the proportion of each material individually. Beyond the limits, the matrix and fiber capabilities can be reversed.

  Thus, the aforementioned structural shape can solve the compatibility problem between the minimum stiffness and damping capacity required for flight. On the other hand, since the matrix or elastic material is confined to the fibers, it provides the mechanical properties required for the fiber rotating surface to work properly. On the other hand, this does not exclude damping and filtering capabilities since it is the main load path because the slotted rotating surface is very rigid.

  An advantage added by the fiber-matrix composite in connection with the coexistence between flight and filtering is that the response to external loads is non-linear. When the slotted rotating surface acts on an elastic base or linear, the external material increases the deformation of the matrix and the latter responds with increased stiffness based on its elastic properties, so that the elastic material is an inelastic base or Acting non-linearly, it contributes to the damping capacity of the device.

  The above phenomenon is very effective when the elastic material is sufficiently confined. This confinement is ensured by the structure of the slotted rotating surface.

  Therefore, when the slotted rotating surface deforms to reduce the thickness of the slot, the elastic material confined in the slot will be compressed and expand in a direction perpendicular to the deformation, and the deformation will be applied to the remaining slots. Partially avoided by the trapped elastic material. Similar effects are achieved by using an angled slot arrangement, whether the deformation is vertical or horizontal.

  Therefore, the passive attenuation device according to the present invention can reduce and / or eliminate vibrations and shock waves generated during the flight of the spacecraft mainly by the spacecraft, and if vibrations and shock waves generated during the flight reach the payload. This will not cause any damage in the payload.

  A detailed description of the invention is provided below with reference to the accompanying drawings.

  FIG. 1 illustrates an attenuator 11 simultaneously connected to an upper interface 12 and a lower interface 13 corresponding to a spacecraft structure capable of flying in outer space.

  In the figure, the following will be understood. The primary structure that provides spacecraft structural connectivity and integrity is a massive cylindrical or conical structure that is nearly rotationally symmetric, which is designed to dampen vibrational phenomena that occur during flight. Because the attenuation coefficient of the body itself is small, it hardly attenuates and sometimes amplifies and propagates to a specific frequency. The device and payload must therefore meet this requirement, complicating the structural design significantly.

  FIG. 2 shows a damping device, which comprises a rotating surface with a circular cross section, for example a linear hollow cylinder 11, with several slots distributed at a predetermined level between vertical sides. For example, four slots in two levels, ie two slots 14 are distributed on each vertical side of the linear cylinder 11.

  Each slot 12 may have a predetermined shape in which the slot 14 extends in a predetermined curve, for example, a circle. For example, the slot 14 passes through a fixed point or apex located on the rotation axis of the linear cylinder 11. It is formed by a line and is circular.

  The slots 14 on both vertical sides of the linear cylinder 11 may be connected in a certain section or may not be connected in another section. This can be seen, for example, in the fragment 14-1 with axes AA 'and BB' shown in FIG. The V-shaped slot 14 in the upper section of the fragment section 14-1 is not connected, but the inverted V-shaped slot 14 in the lower section is connected.

  Accordingly, the central portion of the linear cylinder 11 has a predetermined spool shape, that is, two conical surfaces connected at the apex.

  As shown in FIG. 4, the slot 14 may be formed on the horizontal side surface of the linear cylinder 11. That is, each slot 14 may be formed with a predetermined curvature by a line that moves in parallel and / or moves parallel to the rotation axis of the linear cylinder 11.

  In this case, although the upper slot 14 of the fragment section 14-2 is not connected, the lower slot 14 is connected. Accordingly, the central portion of the linear cylinder 11 has a predetermined H-shape.

  In FIG. 3, the space created by forming the slots or gaps 14 interposed between the sections of the linear cylinder 11 is the same as that of the present invention, such as elastomers, viscoelastic materials, etc. as illustrated in FIGS. It is filled with an elastic material 15 having a small rigidity and a large damping rate, which is also a functional feature of the damping device. The single body ring damping device illustrated in FIGS. 2, 3, 4, 9 and 10 is thus made.

  Therefore, the attenuation device 11 of the cylindrical body has a compact shape equivalent to a fiber resin type composite material in which resin is contained in a space not containing fibers or vice versa. As illustrated in FIGS. 9 and 10, the space in the cylinder 11 that does not contain material is filled with the elastic material 15 or vice versa. This compact and continuous shape is important for the function of the attenuation device, and will be described below.

  The elastic material 15 has two parts or bands, and is an upper stage corresponding to the upper slot 14 and a lower stage corresponding to the lower slot 14 of the cylinder. In FIG. 5, the union section 15-2 of the slot 14 on both sides of the cylinder 11 and the section 15-1 without a union between the slots 14 on both sides can be seen.

  Similarly, FIG. 6 illustrates two portions of elastic material 15 corresponding to the slots of the linear cylinder of FIG. 4, with the slots 14 being formed in the horizontal side or base of the cylinder 11. Similarly, the union section 15-3 of the slot 14 on both sides of the cylinder 11 and the section 15-4 without a union between the slots on both sides can be seen.

  The elastic material 15 on both sides of the slotted cavitation 14 is connected to the compartment 15-3 through each of the slots, that is, has physical continuity, and the elastic material 15 is the outer wall of the linear cylinder 14. Surrounded or separated by It will be appreciated that the enclosure of elastic material 15 may be modified based on the spacecraft flight stage.

  FIG. 7 shows another type of slot 11 in which each layer of the slot is a corrugated continuous or non-continuous curve. The said type of slot 14 is installed in the hollow frustum rotation surface 11 (refer FIG. 8). Similarly, the parallel slot 14 is arrange | positioned at the truncated cone 11 similarly to the rotating surface 11 of a linear cylinder type. This frustoconical shape is suitable for use with adjacent structures of different diameters.

  In FIG. 2, the slotted cylinder 11 is slotted so that the direct load path between the lower interface 13 and the upper interface is always blocked by the slot 14. This is achieved by two levels of different heights in the angled slot 14, as illustrated, for example, in FIGS. The slot 14 forms four conical cavities so that the section in which the linear cylinder 11 is located is divided into three parts divided by V-shaped and inverted V-shaped or U-shaped and inverted U-shaped cavities. .

  These three parts are not completely divided. Rather, the upper stage is connected to the middle stage at at least three locations, and the middle stage and the lower stage are connected at other locations that are offset by 60 ° with respect to the former (see FIG. 13). This is accomplished by preventing continuity in the three compartments of each level slot 14 so that a slotless space is provided, which provides three bridges of a given size. As shown in FIGS. 3, 4, 5, 6, 9 and 10, the load path is narrow.

  Disturbable paths are through six paths between different levels, and thus complex paths. That is, the two-level slot 14 achieves the function of attenuating the shock wave traveling from the lower stage 13 to the upper stage 12 of the spacecraft, and the upper stage 12 has a payload, making it more sensitive to the shock wave. It is high.

  In FIG. 5, when an axial and / or radial load is applied to the load transfer region, the two bands of elastic material 15 are simultaneously subjected to compression-tensile deformation and shear deformation. These loads cause relative movement between the sections of the cylinder 11 separated by the elastic material 15.

  The resistance to movement of these elastic material 15 bands, on the one hand, provides a damping strength which is a movement damping factor based on the reaction of elastic material 15 to shear deformation, on the other hand, more important Of course, when compressive deformation increases, it provides increased stiffness, ie, non-linear behavior. Accordingly, the elastic material 15 contributes to the rigidity of the cylinder, and this contribution is completely compatible with the damping requirement. This will be described below.

  The resistance to deformation provides an increase in stiffness in the damping device, the stiffness being reduced by the slot 14. Furthermore, this stiffness increases the changing nature, i.e. the displacement. The provided stiffness is negligible for the very small displacements that are caused when the impact propagates through the structure. It seems to have hardly occurred. Accordingly, as shown by the arrows in FIG. 11, when an impact disturbance coming from the lower interface 13 attempts to advance toward the upper interface 12, the impact disturbance is reflected by the lower level slot 14, and the three lower paths It progresses from only one of the parts (see the lower part of FIG. 11).

  Following these sections, some of the disturbance is reflected there and the other is circumferentially through the structural portion between the slots 14 as seen in the next level slot 14 where the path is blocked. Proceed (see interruption in FIG. 11). In the upper path, most of the energy is lost. Furthermore, in the process, all natural vibrations in the normal mode of the device formed by the interfaces 12, 13 connected by the damping device are mitigated based on the propagation characteristics of the disturbance.

  FIG. 12 illustrates the operation of the damping device when rigidity is required. This occurs when there are vibrations or gusts in flight that result in significant movement of the spacecraft's center of gravity and during the entire flight to allow control and flight of the hull. In both cases, it is advantageous to have energy dissipation or damping capability. In both cases, if the elastic material 15 is not provided, the slotted linear cylinder 11 is greatly deformed.

  The elastic material 15 is embedded in the slotted cylinder 15 and the elastic material 15 resists resistance to these non-linear deformations, which deformation is shown in the diagram on the right side of FIG. 15 is transmitted in a new load path through 15. This path is in addition to the path of the initial structure, and the path of the initial structure is similar to the shock wave illustrated in the center diagram, as already described, and provides linear stiffness It is what you are doing. With the addition of both actions, the stiffness required for spacecraft flight is achieved without modifying the filter capability determined by the linear action.

  In FIG. 13, what has been described in more detail in three dimensions, the load is transmitted via the linear component of the damping device, and part of the quasi-stationary flow distribution reaching the lower interface 13 is 120 to each other. It is converted into a distribution of three small sections separated by 0 ° and subsequently transmitted to three sectors rotated 60 ° from the previous sector and ends in a quasi-steady flow at the upper interface 12.

  In fact, increasing the damping capacity of the device and reducing steady flow in adjacent structures is achieved by reducing by minimizing load path sections and bridges. To compensate for these effects, nonlinear components and elastic material 15 play a major role due to the compact shape of the device.

  FIG. 14 illustrates how the nonlinear elements of the device are involved. In this case, due to the continuity of the cylinder / elastic material device, the load distribution is kept constant during the entire process. In this way, the overflow effect generated by the linear element on the adjacent structure is partially corrected.

  Similarly, the elastic material 15 is surrounded by the cavities formed by the slots 14 to increase the stiffness action, whether V-shaped, inverted V-shaped, H-shaped or inverted H-shaped.

  The elastic material 15 is compressed between two surfaces that are close to each other but free of edges, so that the volume of the elastic material 15 is maintained and stiffness is reduced. If the edges are closed, expansion of the elastic material 15 is prevented, and the volume reduction only allows the surfaces to approach each other, which is necessary to compress the trapped fluid. Is meant to use energy. Therefore, the rigidity increases. The V-shaped or H-shaped horizontal level of the slot 14 provides a simple and simple confinement.

  This shape of the slot 14 makes it possible to simultaneously work with loads parallel and perpendicular to the surface of the elastic material 15, the latter acting as shear, dissipating or damaging energy and acting as compression. And provides additional rigidity.

  A feature of the damping device in the present invention is the shape of each of the slots 14 distributed in the layers. As shown in FIG. 4, when the slot follows the outer periphery of the cylinder 11, the shape of the slot 14 and the course followed by the slot 14 are, for example, straight lines. In this case, the shear deformation and the compressive deformation of the elastic material 15 have no interaction.

  As shown in FIG. 7, the slot follows a special course to prevent the occurrence of overflow. Similarly, the slot 14 has other types of shapes, such as an ellipse, whose major axis is orthogonal to the axis of the linear cylinder 11 and whose minor axis is parallel to the rotational axis of the linear cylinder 11. There may be.

  The mechanical characteristics of the damping device can be easily changed to meet the various requirements required. For this, it is sufficient to adjust the size of the slot 14 to a compromise between the filter requirements and the mechanical requirements.

FIG. 1 is a perspective view of a structure corresponding to a spacecraft according to the present invention. FIG. 2 is a perspective view of a damping device according to the present invention. FIG. 3 illustrates a two-section cross section of the damping device according to the invention. FIG. 4 illustrates a two-section cross-section of an attenuation device in another embodiment according to the present invention. FIG. 5 is a perspective view of the elastic material of the damping device according to the present invention. FIG. 6 is a perspective view of another elastic material of the damping device according to the present invention. FIG. 7 is another perspective view of the damping device according to the present invention. FIG. 8 is another perspective view of the damping device according to the present invention. FIG. 9 is a perspective view of complementary distributed components of an attenuation device according to the present invention. FIG. 10 is a perspective view of complementary distributed components of an attenuation device according to the present invention. FIG. 11 illustrates the operation of the damping device according to the invention as an impact damping filter. FIG. 12 illustrates how the damping device according to the invention modifies the load path. FIG. 13 is an exploded view illustrating the followability of a linear load path in a damping device according to the present invention. FIG. 14 is an exploded view illustrating the followability of a non-linear load path in the damping device according to the present invention.

Claims (18)

In an attenuation device comprising a rotating surface (11), wherein the rotating surface (11) comprises a set of slots (14) distributed over the rotating surface (11):
The rotating surface (11) is adapted to confine the elastic material (15) within a range defined by the set of slots (14);
Damping device.   Attenuator according to claim 1, wherein the rotating surface (11) has a circular cross section.   3. The damping device according to claim 2, wherein the rotating surface (11) is a linear cylinder.   Attenuator according to claim 2, wherein the rotating surface (11) is a truncated cone.   The damping device according to claim 3 or 4, wherein the set of slots (14) are distributed on both sides of the rotating surface (11).   The damping device according to claim 5, wherein each slot (14) extends in a predetermined curve on one side of the rotating surface (11).   Attenuator according to claim 6, wherein each slot (14) extends with a wave curve.   Attenuator according to claim 6 or 7, wherein the at least one slot (14) is formed by a line passing through a fixed point or vertex and following a predetermined curve.   Attenuator according to claim 6 or 7, wherein the at least one slot (14) is formed by a line moving in parallel and following a predetermined curve.   Attenuator according to claim 8 or 9, wherein at least two ends are parallel, each corresponding to a slot (14) located on one side of the rotating surface (11).   Attenuator according to claim 9, wherein at least two slots (14) are parallel, each of which is located on one side of the rotating surface (11).   12. Attenuator according to claim 10 or 11, wherein at least two slots (14) are in communication via at least one compartment.   11. Damping device according to claim 10, wherein the set of slots (14) forms a spool on the rotating surface (11) formed by two conical surfaces connected at the apex.   13. A damping device according to claim 11 or 12, wherein the set of slots (14) form an H-shape at the rotating surface (11).   A damping device according to claim 1, wherein the elastic material (15) is an elastomer.   The damping device according to claim 1, wherein the elastic material (15) is a viscoelastic material.   17. A damping device according to claim 15 or 16, wherein the elastic material (15) comprises at least one band of elastic material (15).   18. Damping device according to claim 17, wherein the elastic material (15) comprises at least two bands of elastic material (15).

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